The present invention relates generally to optical systems for use in photographic printers, and, more particularly, the invention relates to scanning optical systems using modified Schmidt-type illumination devices for use with photographic printers having spatial light modulators to modulate colored light.
There are numerous types of photographic printers available that range in cost and quality. One of the more common photographic printers uses an area cathode-ray tube ("CRT") to image a photosensitive medium. In this printer, a CRT projects a two-dimensional image through a lens system onto the photosensitive medium. A problem with this printer is its size. The CRT itself is large. The lens system then directs the light through a focal cone that takes a large volume. Due to these factors, the printer becomes relatively large.
Another commercially available printer uses a linear CRT with red, green and blue ("RGB") phosphor stripes and a fiber optic face plate to project an image onto the photosensitive medium as the photosensitive medium moves in a direction transverse to the linear CRT. While some of the size issues are addressed by this printer, the CRT is very expensive, making the printer very costly.
A third type of optical printer uses light emitting diodes ("LED"'s) and lenses to project image-bearing light to an oscillating mirror which directs the image-bearing light in a fast scan direction. Motion of the photosensitive medium relative to mirror is used for slow scan direction. This printer is compact but the optics are expensive.
Accordingly, it is an object of this invention to provide an optical system for a photographic printer that is compact.
It is another object of this invention to provide an optical system for a photographic printer that is inexpensive.
These and other objects of the invention will be obvious and will appear hereinafter.